If I could confiscate the travel documents of just one of the four orchestras visiting the Twin Cities this month to participate in the St. Paul Chamber Orchestra's international festival, I'd victimize the London Sinfonietta, which on Thursday evening presented a mostly British program, led by veteran French conductor Diego Masson, at the SPCO Center.

It's not because the musicians of the Sinfonietta play better than their festival colleagues, or because I loved everything I heard Thursday, that I'm keen to resettle them on our little patch of tundra. It's rather that at a time when classical music has become essentially a "repackaging industry" (to borrow composer Libby Larsen's blunt phrase), the Sinfonietta, which has commissioned or premiered more than 200 pieces over four decades, steadfastly tends the flame of contemporary musical creativity.

Like its continental counterparts, Frankfurt's Ensemble Modern and Paris' Ensemble Intercontemporain, this orchestra (numbering 28 at full strength) collaborates with choreographers, filmmakers and others on eye-catching projects. Less spectacularly (and perhaps more valuably), it incubates composers who may not aspire to marketability but still have compelling things to say. One can quarrel, of course, with the group's aesthetic choices; one can hardly doubt the importance of its enterprise.

Thursday's program, played to a full house, offered works by several composers on whom the Sinfonietta has lavished attention. It opened, fittingly, with Harrison Birtwistle's "Cortege," an unconducted mini-concerto for chamber orchestra that moves its 14 players about the stage. Ceremonial and theatrical, the piece bolsters Birtwistle's reputation as one of the more distinctive figures of the past half-century.

Luke Bedford's captivating settings of five medieval poems, "Or Voit Tout en Aventure," were the evening's surprise. At 30, Bedford is already a master of timbral invention; he's also, to judge from "L'art de Marquet N'a Mesure," a bit of a wag. Soprano Claire Booth, seemingly undaunted by the weather, sang marvelously.

I was less taken with George Benjamin's "Three Inventions," which seemed to need a larger canvas, but was unexpectedly charmed by Pierre Boulez's "Dérive 1," which profited from a suave and exacting performance.

LONDON SINFONIETTA

What: The visiting chamber orchestra plays music of Beethoven and Goebbels (today), and music of Knussen, Boulez, Stravinsky and Birtwistle (Sun.).

Oliver Knussen's "Two Organa" was the felicitous closer. Knussen, the Sinfonietta's conductor laureate, has written that he prefers "to be bewitched for a few minutes than hypnotized for an hour," and these compact pieces, with their bright tintinnabulations, argue his case persuasively.